Gap formation during controlled motion after flexor tendon repair in zone II: a prospective clinical study.

Intratendinous metal markers were used to study the formation of gaps in flexor digitorum profundus tendon repairs during and after early controlled motion with dynamic flexion traction and to evaluate their significance for results in 34 digits with repairs in zone II. The mean (+/- SD) final repair elongation was 3.2 (+/- 3.6) mm. Linear regression analysis showed a general trend toward an inverse relationship between elongation and clinical results in terms of active interphalangeal joint range of motion, but the correlation was weak, and in the individual case gap formation was a poor predictor of clinical result. Gaps of up to 10 mm were quite compatible with good function. The results indicate that controlled motion is effective in restricting the formation of adhesions associated with gap formation during postoperative immobilization.     

Resection of the flexor digitorum superficialis reduces gliding resistance after zone II flexor digitorum profundus repair in vitro

The effect of complete or partial resection of the flexor digitorum superficialis (FDS) tendon on the gliding resistance of the flexor digitorum profundus (FDP) tendon after FDP tendon repair was investigated. Twenty-four human FDP tendons were cut to 80% of their transverse section and repaired with a modified Kessler or a Massachusetts General Hospital augmented Becker suture technique. Gliding resistance was measured with the following constructs: intact state, sutured FDP tendon with FDS tendon intact, sutured tendon without FDS tendon, and sutured tendon with one slip of FDS tendon excised. After FDP repair the gliding resistance after modified Kessler repair increased 247% with FDS intact, 132% with one slip of FDS present, and 103% with FDS entirely removed. With a Becker repair, resistance increased 671% compared with normal with the FDS intact, 379% with one slip of the FDS, and 348% without the FDS tendon. Preserving the whole FDS resulted in a significantly larger increase in gliding resistance after FDP repair than did full or partial FDS removal, which were not significantly different from each other. These results suggest that the FDS tendon affects the gliding resistance under the pulley after FDP repair and that partial FDS excision may facilitate gliding of a bulky FDP repair.     

Flexor digitorum profundus tendon tension during finger manipulation.

Abstract The purpose of this study was to measure the tension in the flexor digitorum profundus (FDP) tendon in zone II and the digit angle during joint manipulations that replicate rehabilitation protocols. Eight FDP tendons from eight human cadavers were used in this study. The dynamic tension in zone II of the tendon and metacarpophalangeal (MCP) joint angle were measured in various wrist and digit positions. Tension in the FDP tendon increased with MCP joint extension. There was no tension with the finger fully flexed and wrist extended (synergistic motion), but the tendon force reached 1.77 +/- 0.43 N with the MCP joint hyperextended 45 degrees with the distal interphalangeal and proximal interphalangeal joints flexed. The combination of wrist extension and MCP joint hyperextension with the distal interphalangeal and proximal interphalangeal joints fully flexed, what the authors term "modified synergistic motion," produced a modest tendon tension and may be a useful alternative configuration to normal synergistic motion in tendon rehabilitation.     

Flexor digitorum profundus tendon to bone tunnel repair: a vascularization and histologic study in canines

PURPOSE: Recent in vivo canine studies have shown incomplete restoration of the flexor digitorum profundus (FDP) insertion site after transection and repair to the cortical surface of the distal phalanx. Previous biomechanical analyses of tendon to bone surface repair have suggested that repair site gap formation of greater than 3 mm occurs frequently under physiologic loads. A recent ex vivo investigation into a novel repair of the FDP tendon into a bone tunnel in the distal phalanx showed improved tensile properties with a decrease in repair site gap formation. Time-zero data, however, do not always accurately reflect in vivo responses. The repair response of the FDP tendon when placed in an osseous compartment is not known. The purpose of this study was to analyze the histologic and vascular anatomic properties of the FDP insertion site after transection and repair in a bone tunnel within the distal phalanx. METHODS: Twenty-six FDP tendon to bone repairs were performed in 13 adult mongrel dogs after insertion site transection. The tendons were repaired in a bone tunnel in the distal phalanx. Vascular analysis of the tendon and repair site was performed by using a modified Spalteholtz technique and routine hematoxylin-eosin staining was used to assess histologic properties of the repair. RESULTS: In normal specimens the vascular analysis showed that there was a distal network of vessels extending 1- to 2-cm proximal to the FDP insertion site. At 10 days after repair the distal tendon segment tendon remained avascular. By 21 days after repair there was proximal migration of an unorganized reticular network of tendon surface vessels with sparse intratendinous communications. At 6 weeks after repair the structure of the distal tendon vascular network resembled that of normals. The vascular response of the tendon within the bone tunnel followed a similar time frame. Histologic analysis showed an inflammatory reaction in the bone tunnel leading to a progressive degradation of that portion of the FDP tendon that resided in the tunnel. Tendon necrosis was not seen. CONCLUSIONS: The FDP tendon, after insertion site transection and repair in a bone tunnel, undergoes a process of neovascularization and revascularization over a period of 6 weeks. There is a progressive loss of tendon parenchyma within the bone tunnel and the suture tracks appeared to serve as conduits for the ingrowth of inflammatory tissue. Restoration of the normal 4-zone tendon-bone interface was not seen. Although ex vivo biomechanical assessment of tendon repair in a bone tunnel appears promising, the repair response in vivo may not be favorable for tendon to bone healing. The progressive tendon degeneration that was observed here may have detrimental effects on repair site tensile properties, increasing the potential for early failure.     

Gliding characteristics of tendon repair in canine flexor digitorum profundus tendons.

The gliding resistance between the flexor digitorum profundus (FDP) tendon and the proximal pulley system was measured using the method of S. Uchiyama, J.H. Coert, L. Berglund, P.C. Amadio, K.N. An (J. Orthop. Res. 13 (1995) 83) in 108 adult dog digits in vitro. The FDP tendons were then lacerated to 80% of their transverse section. Each tendon was repaired with one of the following six suture techniques: Kessler, modified Kessler, Savage, Lee, Becker and simple running suture alone. Each repaired tendon was then tested again using the same method. The Student-Newman-Keuls test for multiple comparisons was performed for statistical analysis. The average gliding resistances of the Kessler, Savage, and Becker repairs were significantly greater than the resistances of the Lee, modified Kessler, and running suture alone repairs (P < 0.05). The Lee suture technique had a significantly greater resistance than the modified Kessler repair and the running suture (P < 0.05). The results of the peak gliding resistance followed the same trends, except that the modified Kessler repair was significantly higher than the running suture alone (P < 0.05). Suture techniques with a multi-strand core suture, with knots located outside the tendon surface, and with multiple-loops on the tendon surface may result in increased gliding resistance between the tendon and pulley system after tendon repair.     

Digital resistance and tendon strength during the first week after flexor digitorum profundus tendon repair in a canine model in vivo

BACKGROUND: After flexor tendon repair, the strength of the repair and the resistance to digital motion are important considerations in deciding when to initiate postoperative rehabilitation. Our objective was to assess these factors in a short-term in vivo canine model of flexor tendon repair. METHODS: Forty-eight dogs were randomly allocated to four groups based on the duration of postoperative follow-up (one, three, five, or seven days). In each group, two flexor digitorum profundus tendons of one forepaw were exposed. One tendon (the repair tendon) was sharply transected and repaired with a modified Kessler suture, and the other one (the sham tendon) was simply exposed without laceration. The involved paw was immobilized until the animal was killed on the designated day. Three tendons from each dog, including the repair tendon, the sham tendon, and a control tendon from a corresponding normal digit on the contralateral side, were tested. RESULTS: The mean peak total digital resistance force in the repair group was lowest at five days (p < 0.01 compared with seven days; p > 0.05 compared with one and three days). The mean peak force needed to overcome the internal gliding resistance between the repaired tendon and sheath was significantly higher than that in both the sham and control groups at all time-points (p < 0.001); however, this value was also smallest at five days. There was no significant difference in suture strength at any time-point (p > 0.05). CONCLUSIONS: When we evaluated tendon-gliding and suture strength after flexor tendon repair, the least favorable ratio of repair strength to force needed to overcome the resistance to digital motion was noted on Day 7, whereas the best combination of tendon strength and low peak resistance force was noted on Day 5.     

Passive and active rehabilitation for partial lacerations of the canine flexor digitorum profundus tendon in zone II.

The purpose of this study was to compare the effect of unrestricted active versus passive mobilization on the gliding function and structural properties (ultimate load and stiffness) of repaired and nonrepaired canine flexor digitorum profundus tendons following partial laceration at 1 week. Using a radiographic method, normalized tendon gliding of the flexor digitorum profundus tendon adjacent to the metacarpal bone and total joint rotation were shown to be significantly greater in passive than in active tendons. Each group differed from their control group, however, by an average of only 5%. Both rehabilitation (active vs. passive) and treatment (repair vs. nonrepaired) of the partial tendon laceration significantly affected gap formation. Both active rehabilitation and repair of the laceration significantly increased gap formation compared with passive rehabilitation and nonrepair of the partial laceration. Rehabilitation did not significantly affect the normalized ultimate loads and stiffness in the passive and active groups but the nonrepair groups displayed significantly higher ultimate loads and stiffness than the repair groups.     

Short-term assessment of optimal timing for postoperative rehabilitation after flexor digitorum profundus tendon repair in a canine model.

Abstract The purpose of this study was to compare the short-term outcome following flexor tendon repair for postoperative rehabilitation commencing on day 1 (a common clinical choice) versus day 5 (the day on which, with postoperative immobilization, the initial gliding resistance is least in this model) in an in vivo canine model. Work of flexion (WOF) and tendon strength were evaluated following tendon laceration and repair in 24 dogs sacrificed 10 days postoperatively. Starting postoperative mobilization at day 5 resulted in no tendon ruptures compared with tendon ruptures in four of the dogs (33%) in the group subjected to mobilization starting at day 1. While there was no statistically significant difference in WOF between groups at day 10, there was a trend toward lower resistance favoring the day 5 start group, and the statistical power to detect a difference in WOF was diminished by the ruptures in the day 1 group. We conclude that starting rehabilitation on day 5, when initial gliding resistance is lower, may have an advantage over earlier starting times, when surgical edema and other factors increase the initial force requirements to initiate tendon gliding. We plan further studies to evaluate the longer-term benefits of this rehabilitation program.     

Effect of synergistic wrist motion on adhesion formation after repair of partial flexor digitorum profundus tendon lacerations in a canine model in vivo.

BACKGROUND: Therapy employing passive finger flexion and active finger extension with the wrist fixed in flexion is commonly used after flexor tendon repair. However, this method of rehabilitation may not produce full tendon excursion because of buckling of the tendon within its sheath with passive flexion. Studies of cadavera suggest that the use of synergistic wrist and finger motion may improve tendon gliding. The purpose of this study was to assess the effects of passive digital motion, performed with either wrist fixation or synergistic wrist motion, on adhesion and gap formation after flexor tendon repair. METHODS: Sixty-six dogs were randomly allocated to two groups. In each group, two flexor digitorum profundus tendons of one forepaw were partially (80%) lacerated and then repaired with a modified Kessler suture. In each group, a different postoperative therapy (wrist fixation or synergistic motion) was performed twice daily. The dogs were killed at one week, three weeks, or six weeks after surgery, and the repaired tendons were evaluated to determine the adhesion grade and adhesion breaking strength. RESULTS: The synergistic motion group had a significantly lower adhesion grade and significantly less adhesion breaking strength than the wrist fixation group at three and six weeks (p < 0.05). At one week, there was no significant difference between the two therapy groups (p > 0.05). CONCLUSIONS: Passive digital flexion and extension with synergistic wrist motion was an effective therapy after repair of partial zone-2 lacerations in a canine model.     

The correlation between controlled range of motion with dynamic traction and results after flexor tendon repair in zone II.

This prospective study investigated the extent to which the range of interphalangeal joint motion during early mobilization with dynamic traction influences the results after flexor tendon repair in zone II. The controlled interphalangeal joint range of motion within the splint was measured 3 weeks postoperatively in 51 digits (48 patients). The active range of motion was measured 4 weeks, 6 weeks, and 1 year postoperatively. Linear regression analysis showed that controlled interphalangeal range of motion had a significant effect on both early and late results. The results provide, for the first time, firm clinical evidence to support the rationale for early mobilization programs designed to maximize controlled interphalangeal joint range of motion.     

Neovascularization of the flexor digitorum profundus tendon after avulsion injury: an in vivo canine study

PURPOSE: The changes in matrix material properties and intrinsic vascularization that have been noted in intrasynovial tendon stumps after avulsion injury may be of considerable clinical relevance with regard to the results of surgical repair. Our objective was to determine both the time course and the source of neovascularization of the tendon stump in an in vivo canine model of flexor digitorum profundus (FDP) avulsion after a clinically relevant delay in diagnosis. METHOD: The FDP tendon was released from bone directly by sharp dissection and the vinculum brevis profundus was lacerated, simulating an avulsion injury with interruption of the vascular supply to the tendon stump. After death at 7 and 21 days, tendon vascularity was evaluated with India ink injection and clearing using a modified Spalteholtz technique. RESULTS: All 7-day specimens showed an absence of vascularity compared with the controls. In all 21-day specimens a direct vascular supply originated from local fibrovascular adhesions contacted the stump on its surface and blood vessels penetrated the tendon stump circumferentially. Progressive vascularization of the avulsed tendon stump occurred between 7 and 21 days after injury, originating from fibrovascular adhesions to the surrounding synovial sheath. CONCLUSIONS: Whereas previous studies of intrasynovial flexor tendon laceration and repair have shown a progressive proximal to distal neovascularization of the FDP during the early postoperative period, longitudinal proximal to distal growth from the proximal blood supply of the FDP was not observed toward the unrepaired tendon stump.     

Repair of zone II flexor digitorum profundus lacerations using varying suture sizes: a comparative biomechanical study

PURPOSE: To compare the maximum tensile load, change in work of flexion, and gapping at the repair site after zone II flexor digitorum profundus tendon repairs using 2-0, 3-0, and 4-0 braided polyester 4-strand locked cruciate repair technique in fresh-frozen cadaveric hands with standard 6-0 suture epitenon repairs, to determine which suture size is the best for a core repair. METHODS: A randomized study was designed using 41 tendons from 15 fresh-frozen cadaveric hands. We included only the flexor digitorum profundus tendons from the index, middle, and ring fingers to minimize variation between digits. Core suture size was randomized for each finger. A sharp laceration through the flexor digitorum profundus in zone II was made and a 4-strand locked cruciate braided polyester core stitch was performed along with a locked epitenon stitch. Cyclic loading was performed for 1,000 cycles. For each tendon the mean work of flexion (before/after zone II repair) and maximum tensile load were measured using a custom-designed tensiometer, as was gapping before maximum tensile loading. RESULTS: Mean gaps after 1,000 load-unload cycles to 3.9 N of pulp pinch did not approach the clinically significant limit of 3 mm in each group. By using a regression model, we found that the prerepair and postrepair comparisons for mean work of flexion to a 3.9-N pulp pinch showed the greatest change in work of flexion for 2-0 braided polyester. Statistical significance was found between 2-0 braided polyester and 3-0 or 4-0 braided polyester; however, the work of flexion between the 3-0 and 4-0 polyester was not clinically significant. The highest maximum tensile load was obtained with suture size 2-0 braided polyester. The maximal tensile load statistically showed 2-0 braided polyester to be stronger than 4-0 braided polyester but we found no statistically significant difference between 3-0 and 2-0 braided polyester or between 3-0 and 4-0 braided polyester. CONCLUSIONS: In this cadaveric study we found that increasing locking cruciate suture caliber from 4-0 to 2-0 increased maximum tensile strength but also caused increased work of flexion. Gapping was not affected by suture caliber. There was no significant difference in strength or mean change in work of flexion between 3-0 or 4-0 braided polyester sutures.     

Functional evaluation after primary flexor tendon repair in zone II

The purpose of this prospective study was to evaluate the results of primary treatment of flexor tendon laceration in zone II according to Verdan's zone system. Special emphasis was given to the postoperative rehabilitation program. Nineteen patients (23 fingers) with laceration of the flexor tendons in zone II were treated operatively. Twelve males and seven females were included in the study. Their mean age was 28 years (range, 16 to 50 years). In 12 cases a concomitant laceration of the digital nerve was present. In all cases primary repair of all injured tendons and nerves was performed and a dorsal splint was applied. On the third to fifth postoperative day an exercise program commenced involving passive flexion-active extension of the injured fingers. Eighteen (22 fingers) of 19 patients completed the follow-up. The results were evaluated according to Strickland's original classification system. The result was excellent in 15 cases, good in five and fair in two. After primary repair of injured flexor tendons, a program of close follow-up, early protected motion and unrestricted motion of the interphalangeal joints offers the best chance of restoring optimal function to the hand.     

Controlled mobilization after flexor tendon repair in zone II: A prospective comparison of three methods

A new controlled-motion program that incorporates dynamic flexion traction to all four digits, a short splint leaving the interphalangeal joints free, and a nighttime extension splint was prospectively compared with a modification of the Kleinert technique and a combination of the modified Kleinert technique and passive movements. Each program was applied to approximately one third of 178 consecutively treated digits with tendon injuries in zone II. The mean total active interphalangeal joint range of motion 6 weeks and 1 year postoperatively was significantly better and extension deficits were significantly less frequent in the digits mobilized with the new program. The postoperative treatment input, in terms of frequency of reviews and time spent in therapy sessions, is not greater than with more traditional controlled-motion programs. Our results indicate that the new program is a safe, reliable, and cost-effective method that produces very good results in a general population.     

Impact of flexor digitorum superficialis on gliding function of the flexor digitorum profundus according to regions in zone II

PURPOSE: Structures and gliding characteristics of the flexor tendons vary remarkably according to regions of zone II in the hand. We studied the impact of the flexor digitorum superficialis (FDS) on the work of flexion and excursion efficiency of the flexor digitorum profundus (FDP) tendon in different regions of zone II. METHODS: Twenty-one fresh-frozen human fingers were used as an experimental model. The FDP was pulled to flex the finger with a tensile machine. The work of flexion of the finger and gliding excursion of the tendon were recorded in the fingers with the FDS intact, after excision of the FDS proximal to, under, or distal to the A2 pulley. RESULTS: The FDS tendon exerts notably different effects on the work of flexion and excursion efficiency of the FDP in subregions of zone II. Removal of the FDS under the A2 pulley affected the FDP most manifestly, causing a 12% decrease in the work of flexion and a loss of the excursion efficiency at the metacarpophalangeal joint. Removal of the FDS proximal to the A2 pulley had a less notable effect on the work of flexion. Removal of the FDS distal to the pulley did not markedly alter the biomechanics of the FDP. CONCLUSIONS: Removal of the FDS tendon in the area of the A2 pulley reduces the work of flexion most notably and causes a loss of excursion efficiency. Removal of the FDS tendon distal to the A2 pulley does not change the work of flexion, and removal of the FDS tendon proximal to the A2 pulley has a notable but less pronounced effect on the FDP tendon.     

Use of a relative motion flexion orthosis after epitendinous zone II flexor tendon repair: A case report

Study designCase reportIntroductionRelative motion flexion (RMF) orthoses are emerging as an option for early active motion (EAM) postoperatively.Purpose of the studyTo describe the rationale and implementation of an RMF orthosis to manage a patient after partial zone II epitendinous flexor tendon repairs.MethodsThis case involves a female who sustained partial flexor tendon lacerations to her middle finger in zone II, 60% flexor digitorum superficialis (FDS) and 90% flexor digitorum profundus (FDP). After epitendinous repair she was referred to therapy for EAM with a no orthosis request. The unusual circumstances prompted the therapist, concerned about the risk of tendon rupture to engage in discussion with the surgeon. Following discussion, a decision was made to use an RMF orthosis for controlled EAM to protect the epitendinous zone II FDS and FDP repairs. Outcomes of range of motion (ROM), total active motion (TAM), %TAM, grip, and quickDASH are reported.ResultsNeither the FDP or FDS tendons ruptured, nor were there any joint contractures. “Good” %TAM outcomes were achieved at 12-week postoperatively. Quick DASH scores improved 61 points indicating a clinically meaningful difference of improved function.DiscussionThe lack of a multi-strand core suture repair is unusual in combination with EAM. The positive outcomes reported in this single patient have raised questions about the protective benefit of the RMF orthosis when used with a zone II epitendinous repair of a 90% FDP laceration. Epitendinous repair of a partial (60%) FDS injury, however, is not uncommon and often not repaired at all.ConclusionsIn this single case report the epitendinous repairs of zone II 90% FDP and 60% FDS with digital nerve involvement were successfully managed with an RMF only orthosis. The use of EAM with an epitendinous repair is in conflict to the current surgical and therapy literature.